||This dissertation reports the work I have completed with two research projects, using paleoecological methods to compare precipitation histories to inform archaeological investigation at two sites. The first chapter will present an analysis of the population history of leporids (rabbits and hares) from Abrigo de los Escorpiones, a shell midden site on the coast of northern Baja California, over the past 10,000 years. Comparison of that population history to sedimentary-based records of the frequency and intensity of El Niño events over the same time period reveals strong correlations between precipitation and overall abundance, taxonomic composition, and age structure of the leporid population at the site. The second chapter of this dissertation reports the results of a multiproxy paleoenvironmental reconstruction of climate during the past 2000 years at a site in Range Creek Canyon, in the Tavaputs Plateau region of eastern Utah. Results from the analysis of fossil pollen, macroscopic charcoal, sediment loss on ignition, magnetic susceptibility, and stable carbon isotope analysis of sediments demonstrate the site was used by human horticulturalists as a maize field during the Fremont occupation of the canyon between roughly AD 800 and AD 1100. Additionally, the paleoenvironmental proxies reveal the period of Fremont occupation of the canyon likely saw less summer precipitation than today, very likely necessitating irrigation of fields for maize horticulturalists.